JP2006237746A - Display device and color balance control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to accurately correct a deviation in the chromaticity due to a secular change or the like with a simple configuration. <P>SOLUTION: The display device includes: a display section (24) for displaying a color image depending on a received image signal; a light detection section (30) for detecting light emission of the display section; and a color balance control section (13) for controlling a color balance of the color image displayed on the display section on the basis of a result of the detection by the light detection section. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a display device and a color balance control method.

  Regarding color balance control of color display devices, general display devices are shipped after controlling the RGB gain to adjust the color balance, and the setting is usually fixed. It is difficult to keep the balance constant. Therefore, there is a method of changing the color balance setting according to the characteristics of the display device according to the usage time. However, in practice, it cannot always be corrected accurately due to the influence of variations in display device characteristics and differences in usage conditions.

  Further, there is a method of controlling a white balance by providing a light-emitting unit for detection outside the screen as in Patent Document 1 below and detecting the light.

JP 2000-115801 A

  The method of providing a display portion outside the screen and detecting the light requires a special display device, and there is no guarantee that the characteristics of the portion outside the screen and the display portion match. Moreover, the installation space of the display part outside a screen may become large, and it may interfere with normal use.

  An object of the present invention is to provide a display device and a color balance control method capable of accurately correcting a chromaticity shift due to a change with time or the like with a simple configuration.

  According to one aspect of the present invention, a display unit for displaying a color image according to an input image signal, a light detection unit for detecting light emission of the display unit, and a detection result of the light detection unit are used. And a color balance control unit for controlling the color balance of the color image displayed on the display unit.

  Since the light emission of the display unit is detected and the color balance is controlled based on the detection result, it is possible to accurately correct the chromaticity shift due to a change with time or the like with a simple configuration.

  FIG. 1 is a block diagram illustrating a configuration example of a plasma display device according to an embodiment of the present invention. In this embodiment, a PDP (plasma display panel) 24 is used as the display unit. The PDP 24 is driven by a dedicated high voltage circuit such as the X driver 21, the Y driver 22, the address driver 23, and the drive circuit 20. These high voltage circuits are controlled by the PDP controller 1. The control unit 1 includes signal processing units 12 and 14 and a timing signal generation unit 15 that are indispensable for driving the PDP 24, a pattern generation unit (supply unit) 11 that is necessary for color balance control, a light detection / control unit 16, and a color balance. The processing unit 13 is added. A base chassis 25 is installed on the back surface of the PDP 24 for support and heat dissipation. The base chassis 25 is provided with a light detection hole (light transmission part) 31 through which light can be transmitted. Although the light transmission part 31 is a light detection hole, it may be a simple gap. In addition, a light sensor 30 is installed so that light from the back surface of the PDP 24 can be received and detected through the light detection hole 31. The output of the light sensor 30 is supplied to the light detection / control unit 16. Further, a light blocking mechanism 33 is installed so that light other than the PDP 24 does not enter the optical sensor 30. The pattern generation unit 11 displays the detection display pattern 32 on the PDP 24, receives the light by the optical sensor 31 through the light detection hole 31, and detects it by the light detection / control unit 16.

The light blocking mechanism 33 blocks light from the outside of the plasma display device to the light sensor 30 so that only light from the PDP 24 enters the light sensor 30 through the light detection hole 31, and other light does not enter the light sensor. Shield from light. Since the chassis 25 is originally intended to support and dissipate heat, it is preferable that the light detection hole 31 has a minimum size. Although the area of the light detection hole 31 depends on the screen size, it is usually preferably 10 cm ² or less.

  In the present embodiment, there is one light detection hole 31 and one light sensor 30, and the pattern generation unit 11 performs RGB detection to detect each of the primary color signals of R (red), G (green), and B (blue). A display pattern for detection corresponding to each of the primary color signals is sequentially generated and light is detected. In accordance with this light detection result, the color balance controller 13 is controlled so that the detection ratio becomes a predetermined value. By performing these series of operations until convergence, the color balance is well controlled. These states will be described later as specific examples of the color balance control algorithm with reference to FIG. Since these controls are performed by displaying a dedicated detection pattern, they cannot be performed in a normal display state. Therefore, in order to execute, it is necessary for the instruction unit 41 to instruct execution when a specific signal is input or a specific operation is performed. Specific examples are (1) when a user inputs a command, (2) when the power is turned off, (3) when the power is turned on, (4) when the usage time exceeds a predetermined value, (5) the accumulated power is When a predetermined value is exceeded, there are combinations thereof.

  The timing signal generator 15 generates a timing signal and supplies it to the drive circuit 20 and the address driver 23. The control circuit 20 controls the X driver 21 and the Y driver 22. The X driver 21 supplies a predetermined voltage to the plurality of X electrodes. The Y driver 22 supplies a predetermined voltage to the plurality of Y electrodes. The address driver 23 supplies a predetermined voltage to the plurality of address electrodes.

  In the PDP 24, the Y electrode and the X electrode form a row extending in parallel in the horizontal direction, and the address electrode forms a column extending in the vertical direction. Y electrodes and X electrodes are alternately arranged in the vertical direction. The Y electrode Yi and the address electrode Aj form a two-dimensional matrix with i rows and j columns. The display cell Cij is formed by the intersection of the Y electrode Yi and the address electrode Aj and the X electrode Xi adjacent thereto corresponding thereto. The display cell Cij corresponds to a pixel, and the PDP 24 can display a two-dimensional image. By performing address discharge between a desired address electrode and Y electrode, the display cell can be selected. Thereafter, by performing a sustain discharge between the X electrode and the Y electrode of the selected display cell, the pixel of the display cell can be turned on.

  The image signal supply source 42 supplies the image signal to the pattern generation unit 11. If the pattern generation unit 11 does not receive an instruction signal for color balance control from the instruction unit 41, the pattern generation unit 11 outputs the image signal from the image signal supply source 42 to the signal processing unit 12. The signal processing unit 12 performs signal processing and outputs it to the color balance control unit 13. The color balance control unit 13 performs color balance control by controlling the RGB gain according to the detection result of the light detection / control unit 16 and outputs the result to the signal processing unit 14. The signal processing unit 14 performs signal processing and outputs the signal to the drive circuit 20. The drive circuit 20 controls the X driver 21 and the Y driver 22 to display an image on the PDP 24. The PDP 24 displays a color image according to the input image signal.

  The instruction unit 41 outputs a color balance control instruction signal in response to a signal input or an operation of an operator. When the pattern generation unit 11 receives an instruction signal for color balance control from the instruction unit 41, the pattern generation unit 11 generates a display pattern for detection and outputs it to the signal processing unit 12. Thereby, the display pattern 32 for a detection is displayed on the upper left part of PDP24 like the above. The optical sensor 30 detects the light emission of the display pattern for detection 32 through the light detection hole 31 from the back side of the PDP 24. The light detection / control unit 16 controls the color balance control unit 13 based on the detection result of the optical sensor 30. The color balance control unit 13 controls the color balance of the color image displayed on the PDP 24 under the control.

  The instruction unit 41 has a power shut-off operator, and when power shut-off is instructed by the operation of the power shut-off operator, first, the light sensor 30 and the light detection / control unit 16 perform light detection, and color The balance control unit 13 can control the color balance and then shut off the power supply. Further, when the plasma display device reaches a predetermined operating time and a power-off instruction is given, the light sensor 30 and the light detection / control unit 16 perform light detection, and the color balance control unit 13 controls the color balance. The power may be cut off after that.

  In addition, the instruction unit 41 has a power-on operation element. When power-on is instructed by operating the power-on operation element, the light sensor 30 and the light detection / control unit 16 first perform light detection. The color balance control unit 13 can also control the color balance. In addition, when the plasma display device reaches a specific operating time and is instructed to turn on the power, the light sensor 30 and the light detection / control unit 16 perform light detection, and the color balance control unit 13 controls the color balance. You may make it perform.

  FIG. 2 is a circuit diagram illustrating a configuration example of the optical sensor 30 and the light detection / control unit 16. The light detection / control unit 16 includes resistors R1 and R2, an operation (OP) amplifier 201, a capacitor C1, and a microprocessor (MPU) 202. The MPU 202 has an A / D converter 203. The resistor R2 and the capacitor C1 constitute a low pass filter (LPF) 204.

As the optical sensor 30, an amorphous silicon photosensor having characteristics close to human visibility characteristics is suitable, and an example in that case will be described. When the optical sensor 30 receives light, a current I1 corresponding to the amount of received light flows. This current I1 is amplified using the operational amplifier 201, converted into a voltage V1, passed through a low-pass filter 204, converted from an analog format to a digital format by an A / D converter 203, and taken into the MPU 202. The voltage V1 is expressed by the following equation.
V1 = I1 × R1

  FIG. 3 is a flowchart showing a specific example of the light detection algorithm. In step S301, the PDP 24 is set to a non-display state. Next, in step S302, light detection is performed in this state, and the detected voltage is set to V0. Next, in step S303, the red detection display pattern 32 is displayed on the PDP 24. Next, in step S304, light detection is performed in the display state, and the detected voltage is set to Vr. In step S305, the green detection display pattern 32 is displayed on the PDP 24. Next, in step S306, light detection is performed in the display state, and the detected voltage is set to Vg. In step S307, the blue detection display pattern 32 is displayed on the PDP 24. Next, in step S308, light detection is performed in the display state, and the detected voltage is set to Vb. Next, in step S309, Vr-V0 is set as the red detection voltage Vrc, Vg-V0 is set as the green detection voltage Vgc, and Vb-V0 is set as the blue detection voltage Vbc.

  As described above, in order to eliminate the influence of noise or the like and increase the accuracy, detection is first performed in a non-display state where the detection display pattern 32 is not generated, and then the detection display pattern 32 is displayed and detected, and the difference Have taken. In order to further improve the accuracy, detection may be performed a plurality of times and the average may be taken.

  FIG. 5 is a flowchart showing a specific example of the color balance control algorithm. In step S501, the red detection voltage Vrc, the green detection voltage Vgc, and the blue detection voltage Vbc are detected by the process of FIG. Next, in step S502, the light emission ratio (light quantity ratio) Lrc: Lgc: Lbc of each color of the PDP 24 is calculated based on the voltages Vrc, Vgc, and Vbc. Next, in step S503, it is checked whether or not the detected light emission ratio Lrc: Lgc: Lbc matches a specific light emission ratio Lrr: Lgr: Lbr. The specific emission ratio is individually set for each plasma display device based on the actual light detection result at the time of shipment of the plasma display device from the factory. If they do not match, the process proceeds to step S504, and if they match, the process ends. In step S504, color balance adjustment is performed so that the above light emission ratios match, and the process returns to step S501. The above process is repeated until a specific emission ratio is reached.

  4A to 4E are diagrams illustrating specific examples of the optical sensor 30, the light detection hole 31, and the display pattern 32 for detection. There are various methods depending on the type of the optical sensor 30 used.

  FIG. 4A shows a method in which one photosensor 30 and one photodetection hole 31 are used. The pattern generation unit 11 displays the detection display patterns 32 of the plurality of colors (RGB) on the PDP 24 while shifting the time. The optical sensor 30 is. All of the light of a plurality of colors can be detected, that is, it has a detection sensitivity of a band that includes the visibility band and beyond. The optical sensor 30 performs light detection each time the detection display pattern 32 for each color is displayed on the PDP 24. This method is a suitable method when the optical sensor 30 is similar to the visibility, and the detection display pattern 32 is sequentially generated corresponding to each of RGB, and detection is performed three times. Although it takes time, using the same optical sensor 30 makes the detection error common and cancels it.

  FIG. 4B is a system using three each of the optical sensors 30r, 30g, 30b, the light detection holes 31r, 31g, 31b, and the detection display patterns 32r, 32g, 32b, and performs detection independently of RGB. The optical sensor 30r detects the light of the red detection display pattern 32r through the light detection hole 31r. The optical sensor 30g detects the light of the green detection display pattern 32g through the light detection hole 31g. The optical sensor 30b detects light of the blue detection display pattern 32b through the light detection hole 31b. The display patterns for detection 32r, 32g, and 32b are displayed in a color that matches each of the RGB colors, so that all of the RGB light can be detected. 32b can be used. Further, if the optical sensors 32r, 32g, and 32b having sensitivity characteristics specialized for RGB emission wavelengths are used, the detection display patterns 32r, 32g, and 32b may be white.

  FIG. 4C shows a method using one light detection hole 31, three light sensors 30r, 30g, 30b and three detection display patterns 32r, 32g, 32b. The optical sensors 30r, 30g, and 30b detect the light of the light detection patterns 32r, 32g, and 32b through the common light detection hole 31, respectively. Except for the point that there is one light detection hole 31, it is the same as FIG.

  FIG. 4D shows a method using three optical sensors 30r, 30g, 30b, three optical filters 34r, 34g, 34b, and three light detection holes 31r, 31g, 31b. The detection display pattern 32 is common and basically displays in white. The optical sensors 30r, 30g, and 30b match the visual sensitivity, and can detect all RGB light. The optical filters 34r, 34g, and 34b are wavelength selection filters disposed in front of the optical sensors 30r, 30g, and 30b, and transmit RGB light, respectively. That is, the optical sensor 30r allows only red light to pass, the optical sensor 30g allows only green light to pass, and the optical sensor 30b allows only blue light to pass. The optical sensors 30r, 30g, and 30b can detect RGB by detecting light transmitted through the optical filters 34r, 34g, and 34b, respectively. The optical filters 34r, 34g, and 34b are filters that selectively transmit light having a specific wavelength corresponding to RGB, but bandpass filters having a certain transmission wavelength width may be used.

  FIG. 4E shows a method using three optical sensors 30r, 30g, 30b, three optical filters 34r, 34g, 34b, and one light detection hole 31. This method is the same as that shown in FIG. 4D except that one photodetection hole 31 is commonly used by the three photosensors 30r, 30g, and 30b. The optical sensors 30r, 30g, and 30b detect light of the white detection display pattern 32 through the common light detection hole 31 and the optical filters 34r, 34g, and 34b.

  FIG. 6 shows a configuration example showing the arrangement relationship between the detection display pattern 32 and the optical sensor 30 in FIG. The optical sensor 30 corresponds to the three optical sensors 30r, 30g, and 30b in FIG. The detection display pattern 32 corresponds to the three detection display patterns 32r, 32g, and 32b in FIG. The light shielding mechanism 33 shields light from the outside of the plasma display device with respect to the optical sensor 30. In FIG. 1, during color balance control, normal image display is not performed, but only the dedicated display pattern for detection 32 is displayed. That is, when displaying the detection display pattern 32, the PDP 24 does not display an image corresponding to the input image signal. On the other hand, in FIG. 6, a part of the lower left part of the normal display screen is replaced with the detection display pattern 32 to perform color balance control. That is, the PDP 24 replaces a part of the image corresponding to the input image signal with the detection display pattern 32 and displays it. The color balance is controlled while displaying the detection display pattern 32 in one corner of the lower left corner of the screen. Since normal display images are not disturbed, color balance control can be performed at any time. In this case, in order to detect light at the same timing, the system uses three optical sensors 30 that detect light independently for each of RGB. Of course, it is needless to say that a sequential detection method using the same optical sensor is also possible.

  As described above, in the present embodiment, the optical sensor 30 is provided on the back surface of the PDP 24, and the color balance of the actual display is determined by detecting the intensity of light derived from the back surface of the PDP 24 for each color. Control color balance. Feedback control is performed by taking out display light from the back surface of the PDP 24 and detecting it with the optical sensor 30. By extracting light from the back surface of the PDP 24, a PDP 24 having only a normal display area can be used instead of a special PDP 24. In addition, since the actual light emission intensity is detected and feedback control is performed, it is accurate without being affected by variations in the characteristics of the PDP 24 or differences in usage conditions. As a result, it is possible to correct the chromaticity shift (color balance) due to a change with time or the like because the actual light emission can be feedback-controlled while having a simple configuration in which light is extracted from the rear surface of the PDP 24 and detected.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

  The embodiment of the present invention can be applied in various ways as follows, for example.

(Appendix 1)
A display unit for displaying a color image in accordance with the input image signal;
A light detection unit for detecting light emission of the display unit;
And a color balance control unit configured to control a color balance of a color image displayed on the display unit based on a detection result of the light detection unit.
(Appendix 2)
The display device according to appendix 1, wherein the light detection unit detects light emission of the display unit from a back side of the display unit.
(Appendix 3)
The light detection unit performs first light detection when the display unit is not displaying, performs second light detection when the display unit is displaying, and performs the first and second light detections. The display device according to attachment 1, wherein a difference between detection results is output as a light detection result.
(Appendix 4)
The display device according to claim 1, wherein the light detection unit performs light detection for each of a plurality of colors, and the color balance control unit controls the light amount ratio of the plurality of colors to be a specific ratio.
(Appendix 5)
The display device according to appendix 4, wherein the specific ratio is individually set for each display device.
(Appendix 6)
The display device according to appendix 1, wherein the light detection unit detects a plurality of times and outputs an average value as a light detection result.
(Appendix 7)
Furthermore, it has a pattern supply unit for displaying the display pattern for detection on the display unit,
The display device according to claim 1, wherein the light detection unit performs the light detection when the display pattern for detection is displayed on the display unit.
(Appendix 8)
The display device according to appendix 1, wherein the light detection unit includes a plurality of optical sensors for detecting light of a plurality of colors, respectively.
(Appendix 9)
The light detection unit is
A plurality of light sensors capable of detecting all the light of a plurality of colors;
A plurality of optical filters disposed in front of the plurality of photosensors and respectively transmitting the plurality of colors of light;
The display device according to appendix 1, wherein each of the plurality of optical sensors detects light transmitted through the plurality of optical filters.
(Appendix 10)
Furthermore, it has a pattern supply unit for displaying the display pattern for detection of each of a plurality of colors on the display unit with a time shift,
The light detection unit includes a light sensor capable of detecting all of a plurality of colors of light,
The display device according to appendix 1, wherein the light sensor performs light detection each time a display pattern for detection of each color is displayed on the display unit.
(Appendix 11)
The display device according to appendix 1, wherein the color balance control unit controls the color balance in response to a signal input or an operation of an operator.
(Appendix 12)
The display device according to claim 1, wherein when the power-off is instructed, the light detection unit performs the detection, the color balance control unit performs the color balance control, and then the power is cut off.
(Appendix 13)
The display device according to claim 1, wherein when a power-on is instructed, the light detection unit performs the detection, and the color balance control unit controls the color balance.
(Appendix 14)
When the display device reaches a specific operating time and a power cut-off is instructed, the light detection unit performs the detection, the color balance control unit performs the color balance control, and then the power is cut off. The display device according to appendix 12.
(Appendix 15)
14. The display device according to supplementary note 13, wherein when the display device reaches a specific operating time and power-on is instructed, the light detection unit performs the detection, and the color balance control unit performs the color balance control.
(Appendix 16)
The display device according to appendix 1, wherein the display unit is a plasma display panel.
(Appendix 17)
The display unit has a chassis having a light transmission part capable of transmitting light on the back surface,
The display device according to appendix 2, wherein the light detection unit detects light emission of the display unit from the back surface of the display unit through the light transmission unit.
(Appendix 18)
The display device according to appendix 17, further comprising a light-shielding unit for shielding light from outside the display device in the light detection unit.
(Appendix 19)
The display device according to claim 17, further comprising a light shielding portion for shielding only the light of the display portion from entering the light detecting portion through the light transmitting portion and preventing other light from entering the light detecting portion. .
(Appendix 20)
The display device according to appendix 17, wherein an area of a light transmission portion of the chassis is 10 cm ² or less.
(Appendix 21)
The display device according to appendix 7, wherein the display unit does not display an image corresponding to an input image signal when displaying the display pattern for detection.
(Appendix 22)
The display device according to appendix 7, wherein the display unit displays a part of the image corresponding to the input image signal by replacing the display pattern for detection.
(Appendix 23)
A color balance control method for a display device having a display unit for displaying a color image according to an input image signal,
A light detection step of detecting light emission of the display unit;
A color balance control method comprising: a color balance control step for controlling a color balance of a color image displayed on the display unit based on the detection result.

It is a block diagram which shows the structural example of the plasma display apparatus by embodiment of this invention. It is a circuit diagram which shows the structural example of a photosensor and a photon detection / control part. It is a flowchart which shows one specific example of a light detection algorithm. 4A to 4E are diagrams illustrating specific examples of the optical sensor, the light detection hole, and the display pattern for detection. It is a flowchart which shows a specific example of a color balance control algorithm. FIG. 5 is a diagram illustrating a configuration example illustrating a positional relationship between the detection display pattern and the optical sensor in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 PDP control part 11 Pattern generation part 12 Signal processing part 13 Color balance processing part 14 Signal processing part 15 Timing signal generation part 16 Photodetection / control part 20 Drive circuit 21 X driver 22 Y driver 23 Address driver 24 PDP
25 Base chassis 30 Photosensor 31 Photodetection hole 32 Display pattern for detection 33 Light shielding mechanism 41 Indicator 42 Image signal supply source

Claims (10)

A display unit for displaying a color image in accordance with the input image signal;
A light detection unit for detecting light emission of the display unit;
And a color balance control unit configured to control a color balance of a color image displayed on the display unit based on a detection result of the light detection unit.   The display device according to claim 1, wherein the light detection unit detects light emission of the display unit from a back side of the display unit.   The light detection unit performs first light detection when the display unit is not displaying, performs second light detection when the display unit is displaying, and performs the first and second light detections. The display device according to claim 1, wherein a difference between detection results is output as a light detection result.   The display device according to claim 1, wherein the light detection unit performs light detection for each of a plurality of colors, and the color balance control unit controls the light amount ratio of the plurality of colors to be a specific ratio. Furthermore, it has a pattern supply unit for displaying the display pattern for detection on the display unit,
The display device according to claim 1, wherein the light detection unit performs the light detection when the display pattern for detection is displayed on the display unit. The display unit has a chassis having a light transmission part capable of transmitting light on the back surface,
The display device according to claim 2, wherein the light detection unit detects light emission of the display unit from a back surface of the display unit through the light transmission unit.   The display device according to claim 6, further comprising a light-shielding unit for shielding light from outside the display device in the light detection unit.   The display device according to claim 5, wherein the display unit does not display an image corresponding to an input image signal when displaying the detection display pattern.   The display device according to claim 5, wherein the display unit displays a part of the image corresponding to the input image signal by replacing the display pattern for detection. A color balance control method for a display device having a display unit for displaying a color image according to an input image signal,
A light detection step of detecting light emission of the display unit;
A color balance control method comprising: a color balance control step for controlling a color balance of a color image displayed on the display unit based on the detection result.

Images